Java class variable that tracks number of objects instantiated

Question

I have this class, Student, with the variable StudentID:

public class Student extends Person{
  int studentID = 0;
  int level;

  public Student(){

  }         


        

Answer 1

Add a static counter and initialize studentID with it, incrementing it in the process :

public class Student extends Person{
  static counter = 1;
  int studentID = counter++;
  ...